A Prius That Gives Back To The Grid

Engineers at the University of Technology Sydney have built a plug-in Toyota Prius they claim is capable of reducing power shortages by returning energy to the grid.

The “Switch” prototype sports an extra battery pack that allows it to take power from a household power supply – or send it back. It also creates a means of storing renewable energy, such as wind, that is often produced at off-peak times. The researchers claim the technology could revolutionize the automotive industry.

“The vehicle-to-grid technology this car presents could do for the automotive industry and the electricity industry what the personal computer did for computing, and what the mobile phone did for telecommunications,” Chris Dunstan, the project director, told the Sydney Morning Herald.

Most major car companies are developing EVs, which has many people wondering where all that electricity will come from. V2G helps alleviate that problem because the extra battery can store energy at off-peak times and feed it back into the grid at times of peak demand, says Project Research Consultant Josh Usher.

“We have been working on plug-in hybrids for a few years now, and we are also involved in a collaborative research project entitled the Intelligent Grid,” Usher told Wired.com. “It seems logical to combine our research in electricity grids with our research in electric cars by making vehicles fully grid interactive.”

The extra lithium iron phosphate battery in the Switch prototype’s trunk provides an extra 4.1 kWh and 256 volts. The PHEV pack, manufactured by K2 Energy Solutions, helps maintain a charge in the Toyota’s existing NiMH battery pack and raises fuel economy to 118 mpg. There are two plugs on the back bumper – one for charging, and one for returning power to the grid.

“The car can be plugged into a grid synchronous inverter, commonly used in solar PV rooftop systems, and you can simply flick a switch to begin feeding energy from the battery pack into the grid,” said Usher. That’s the inverter in the picture. “Moreover, the car’s fuel economy is highly dependent on driving style. In Sydney, I’ve been able to achieve a fuel economy of under 1L/100 km (235mpg) for distances up to 40km (25mi) with careful driving.”

Usher is lobbying the Australian government and businesses to bring this technology to production. They’ve spent about $45,000 developing the prototype. He believes it would cost automakers far less than that.

“It could cost car companies as little as a few hundred dollars to provide this functionality with their plug-in hybrid or electric vehicles in large volumes,” he said.

The Australian Department of Environment and Climate Change says the UTS prototype would cost as little as 50 cents a day to charge with off-peak power, and energy companies could compensate motorists for pumping electricity back into the grid.

“We know that people want to play their part when it comes to reducing their impact on the environment,” Carmel Tebbutt, deputy prime minister of New South Wales, said in a statement (.pdf). “Switch not only saves up to 2.8 tonnes (about 3 tons) of greenhouse gas emissions a year compared to an average car – it also acts as a portable storage unit for renewable energy.”

In addition to reducing one’s carbon foot-print, Tebbutt claims the V2G prototype could eliminate the need to build expensive power stations and network infrastructure while supporting such renewable energy sources as solar and wind by storing energy at times of peak power generation for use later.

The government of New South Wales wants to cut motor vehicle pollutants in half by 2020 and has added a Switch Prius to its fleet. The government is expected to introduce a power “feed-in” tariff by the middle of this year to spark demand for V2G technology from motorists Down Under.

“You could envisage a world in the future where many people have these cars and there is an opportunity to say ‘tomorrow we need everyone to feed their cars back into the grid’, and that will help us address a power need on that particular day,” Tebbut said. “There would obviously need to be a financial incentive for people to do that, but we’re a long way away from that at the moment.”